In semiconductor processing, interconnects are used to provide electrical connection between adjacent semiconductor dies. For vertically stacked semiconductor dies, through-silicon vias (TSV) are often used. Such TSVs on adjacent semiconductor dies are typically electrically connected to each other using direct physical coupling in which the bond pads of one die are directly bonded to the bond pads of the other.
Direct bonding of interconnects requires relatively large bond pads (e.g., 45×45 microns or larger) and also results in relatively high power consumption and current drop. Proximity coupling, which is an alternative to direct bonding, involves positioning the conductive pads of one die adjacent to, but physically separated from, the conductive pads of another die. In proximity coupling, there is a gap that is not filled with a conductive material between the adjacent pairs of bond pads. Proximity coupling interconnects rely on either magnetic flux (inductive coupling) or electric field (capacitive coupling) to serve as the medium through which signals are transmitted between the adjacent conductive pads. Proximity coupling can achieve lower power consumption and lower current drop than direct physical coupling. Additionally, proximity coupling can be utilized with significantly smaller conductive pads (e.g., on the order of 5×5 microns, 20×20 microns, or larger). However, the use of smaller conductive pads for proximity coupling also requires more precise alignment between adjacent conductive pads. Additionally, the vertical distance between the adjacent conductive pads must be controlled precisely to achieve effective coupling. While proximity coupling interconnects have been demonstrated in principle, there remains a need to develop practical methods to incorporate proximity coupling interconnects into packaging systems and methods utilizing standard semiconductor processing techniques.